Some of the existing lancing apparatuses include a lancet holder that holds a lancet, which is caused to move together with the lancet holder so as to stick into a skin (see JP-A-2001-425 for example). The lancing motion of the lancing apparatus disclosed in this document can be achieved by the structure of a lancing apparatus 9 shown in FIGS. 32A-32C. The lancing apparatus 9 utilizes the spring force of a coil spring 90, thereby moving a lancet 92 together with a lancet holder 91.
In the lancing apparatus 9, as shown in FIG. 32A, an engaging hook 93 of the lancet holder 91 is latched on a stepped portion 95 of the housing 94, so that the coil spring 90 can store the spring force. When an operating knob 96 is pressed down, a working portion 97 of the operating knob 96 acts on the engaging hook 93 as shown in FIG. 32B, so as to release the engaging hook 93. This permits the spring force of the coil spring 90 to act on the lancet holder 91 as shown in FIG. 32C, so that the lancet 92 is moved in a lancing direction N1 together with the lancet holder 91.
As is apparent from FIG. 32C, in the lancing apparatus 9 the lancet 92 is inserted into a bore 98 of the lancet holder 91, to be retained. The lancet 92 is retained by friction between the outer surface of the lancet 92 and the inner surface of the bore 98. With such an arrangement, a relatively large frictional resistance is required between the outer surface of the lancet 92 and the inner surface of the bore 98, in order to enable the lancet holder 91 to firmly retain the lancet 92. Conventionally, it is difficult to check whether the lancet 92 has been fully inserted into the bore 98 of the lancet holder 91, when loading the lancet 92 in the bore 98. The structure of the lancing apparatus 9 allows the lancing action to be performed regardless of whether the lancet 92 is fully inserted into the bore 98. Thus, it could happen that the lancing action may be performed, with the lancet 92 inserted only halfway into the bore 98. In this case, the lancet 92 may stick too deeply into the skin. Further, the large frictional resistance between the outer surface of the lancet 92 and the inner surface of the bore 98 incurs additional drawbacks. For example, it requires a relatively large force for inserting the lancet 92 into the bore 98, and also makes it difficult to remove the lancet 92 from the lancet holder 91.
It could be an option to redesign both of the lancet and the lancet holder so as to allow the lancet to be securely loaded in position on the lancet holder and to be easily removed from the holder, in order to eliminate the foregoing drawbacks. Redesigning the shape of the lancet, however, reduces the compatibility of the lancet with different types of lancing apparatuses, thus spoiling the versatility of the lancet.